Air temperature control for carburetors



Nov. 4, 1952 SWEENEY 2,616,675

AIR TEMPERATURE CONTROL FOR CARBURETORS Filed June 26, 1947 3Sheets-Sheet 1 INVEN TOR. FRANK B. SWEENEY ATTORNEY Nov. 4, 1952 F. B.SWEENEY 2,616,675

AIR TEMPERATURE CONTROL FOR CARBURETORS Filed June 26, 1947 3Sheets-Sheet 2 2% 4-: I IH 2 n:

Q g m N Q5 L INVENTOR.

FRANK B. SWEENEY A T TORNE Y Nov. 4, 1952 SWEENEY 2,616,675

AIR TEMPERATURE CONTROL FOR CARBURETORS Filed June 26, 1947 3Sheets-Sheet 5 INVENTOR. FRA/VKB. SWEENEY ATTORNEY Patented Nov. 4, 1952AIR TEMPERATURE CONTROL FOR CARBURETORS Frank B. Sweeney, Rochester, N.Y., assignor to Bitter Company, Inc., Rochester, N. Y., a corporation ofDelaware Application June 26, 1947, Serial No 757,159

1 Cl Q aim My invention relates to an air temperature ;control forcarburetors employed in gasoline engine propelled craft. lhisapplication is a division of my application Serial Number 630,257, filedNovember 23, 1945, and now Patent Number 2,574,670, issued November 13,1951.

An object of my invention is to provide a simplified and efiicienttemperature control for the air flowing to the carburetor of an internalcombustion engine.

More specifically, my invention contemplates an air temperature controlfor the air flowing to the carburetor of an internal combustion enginewherein an air metering valve is provided in the air passage to thecarburetor and air may flow through the air metering valve either fromthe atmosphere or through apassage open to atmosphere which is connectedto a point adjacent the engine exhaust manifold, the arrangement beingsuch that air is taken either from the connection to atmosphere or theconnection adjacent to the exhaust manifold in accordance with thetemperature conditions of the engine, the arrangement further beingsuchthat all of the air regardless of where it is taken from passesthrough the air metering valve so that accurate control of theair-gasolineratio supplied tothe carburetor is possible.

Other objects and advantages of my invention will be set forth moreparticularly in the claim and will be apparent from the followingdescription, whentaken in connection with the accompanying drawings, inwhich:

Fig-. 1 is aviewpartly in section and partially diagrammaticillustratingthepressure injection carburetor of my invention;

Fig'. 2 is a side elevation of a portion of Fig. l, as" indicated by thearrows along the line of 2--2 of- Fig. 1;

Fig. 3* is a sectional view taken substantially on the line 3-3 of Fig.1 in the direction indicatedby the arrows;

Fig; 4' is a view partly in section looking from the right of Fig. 3and. with the cover plate of the compartment which houses the airtemperature control removed;

Fig. 5 is: a side elevation of the pressure injectioncarburetor of myinvention looking from the left of Fig. l; i

Fig. '6' is an enlarged sectional view of a portogether, as shown atl3.v The carburetor is connected to the intake manifold, partiallyindicated at M, of the engine with which the carburetor is associated.Above the mixing chamber section 12 is an air intake section 15. Theparticular carburetor illustrated is of the down-draft type which is thepreferred form. However, this is primarily for purposes of illustrationvas the principles of my invention may be incorporated in other types ofcarburetors.

The carburetor is provided with the usual throttle-valve I 6, mounted.on a shaft IT, carried in bores. formed in bosses. The function andoperation of a throttle valve are well known in the art to which thisinvention applies and no description of its function and operation isbelieved to be necessary. The main body section and the mixing chambersection are provided with passages which are connected to form an airflow passage. l8 through which air flows to the intake manifold of theengine under the. partial vacuum or subatmospheric pressure conditionscreated by the reciprocation of the pistons thereof.

The air flow passage it is normally almost closed by an air meteringdisc l9 which is movable from the closed position shown to a partiallyor fully open position, in accordance with the differential in pressureexistent on opposite sides of the air metering disc. The air meteringdisc assumes a position dictated by the pressure conditions existent-andthus its position reflects or measures the volume of air passing throughthe air flow passage. While I have showna disc air metering device andbelieve that this has distinct advantages, other air metering devicesmight be employed in combination with other parts of the carburetor ofmy invention.

The air metering disc Hi is connected, in a manner presently described,to a fuel metering valve generally indicated by the numeral 2-]. Thefuel metering valve is located in the fuel line, generally designated bythe numeral 22, the fuel line being connected to a fuel pump diagrammatical-ly illustrated by the numeral 23'.

The fuel pump 23 is driven in the usual manner from the engine cam shaftand is of a type in common use adapted to deliver gasoline to the fuelline at a substantially constant pressure regardless of engine operatingspeed. The fuel pump 23 is connected to the fuel line by a pipe 2% whichextends into a threaded opening formed in the main body section of thecarburetor. A bore 26-, communicating with the pipe 2 opens into achamber '21 in which is housed. a strainer 28. Access to the chamber 27and the strainer 23 for the purpose of cleaning the same, is gainedthrough an opening in the main body section which is closed by athreaded cap 29.

The chamber 27 is in communication with an enlarged opening in the mainbody section which is adapted to receive a regulating valve assembly,generally indicated by the numeral 3 i. The regulating valve assembly 3icomprises a valve body section 32 and a cap section 33. The valve bodysection 32 is supported by an annular wall provided in the casting whichforms the main body section II of the carburetor. Interposed between thefacing surfaces of the valve body section 32 and the annular wall formedin the casting is a gasket 34 to prevent leakage of fuel as will laterappear. The cap section 33 of the regulating valve assembly is threadedinto the casting as shown at 35. By threading the cap section inward,pressure is applied on the gasket 34 so as to form a seal between thesurfaces.

The lower end of the valve body section 32, is provided with a valveseat 3! formed at the end of a bore 38. The bore 38 constitutes a partof the fuel line 22. Extending from the bore 2 8 are one or more radialpassages 39 which open into an annular recess M. The annular recesscommunicates with a transversely extending passage 42, one end of whichis closed by a plug ii! and which also constitutes part of the fuel line22. The transverse passage d2 connects with a vertically extendingpassage 43 formed in an upwardly extending part 34 (Fig. 7) which housesthe fuel metering valve assembly 2!. The pressure regulating valve 3!,its function and operation are described in my above mentionedapplication and such description need not be repeated herein.

As shown most clearly in Fig. 6, the fuel metering valve 2i includes afrusto-conical valve element 7'3, normally adapted to engage a seat 18,formed on the end of a valve housing member 19. The valve housing memberis threaded into telescopic relation with the upwardly extending part 44of the main casting of the carburetor, as shown at 8|. The valve elementH is integral with a valve stem 8E which is reciprocable in a bore 83formed in the valve housing member is. The upper end of the valve buttsagainst the lower end of a stem 85 connected to the air metering disc!9.

Adjacent its upper end the stem 35 is provided with a shoulder 84 uponwhich i seated disc elements, generally indicated by the numeral 86. Theupper end of the stem is threaded to receive a nut 87, a washer 88 and abacking plate 85 lying beneath the nut and being confined thereby. Theair metering disc is preferably circular and has a pair of openings orports 9 i A fiat thermostatic spring element 9?. lies beneath thebacking plate 89 and normally closes the ports 9i. However, undercertain conditions of operation, as will presently appear, thethermostatic spring element 532 when heated may curl upwardly to uncoverthe ports 9!.

The valve housing 79 at its lower end, has an enlarged part 93 of thebore and above this is formed a cylindrical portion 9-4 of reduceddiameter which constitutes a part of the metering section of the valve.Above the metering section is an enlarged portion 53 which connects withradial passages 9'! which open into recesses 98 communicating with fuelnozzles 99 and iiii. The valve stem has a cylindrical part Hi2 normallysubstantially in registry with the enlarged bore 93. Above thecylindrical part 582 is a tapered or other accurately formed section I03which, when the valve ll, E8 is in a partially open position, registerswith the cylindrical metering section 95.

Above the metering section of the valve stem is a part 16 of reduceddiameter and above the reduced part 134 is a cylindrical section 566which forms the abutment which is engag d by the end of the disc stem85. The disc stem has a shoulder it? adapted to engage a shoulder 408formed in the bore 33 to limit the upward movement of the air meteringdisc. A spring N39 is seated in the bottom of the passage 43 and engagesthe bottom of the valve stem, as shown at Hi), to urge the valve stemand the disc stem in an upward direction to close the fuel valve and theair metering disc. Since movement of the air metering disc istransmitted to the fuel metering valve element l? by the abuttingrelation of the stems, the fuel valve stem is substantially freefloating so that the valve element i? will accurately engage its seati8.

At the upper end of the valve housing 79, a spring H3 is coiled aroundthe circumference of the valve housing, as shown, and its end H4encircles and presses on the disc stem. This pressure exerted on thestem dampens the vibration of the parts.

As shown in the drawings ,even when the valve element "El is on its seat'58, a clearance exists at the metering gap between the metering sectionQ4 of the valve housing and the tapered metering section iii of thevalve stem. However, as soon as the valve element l7 moves off its seat,the flow of fuel to the engine nozzles comes under the control of thefuel metering elements 94, E33. Downward movement of the valve stemincreases the clearance between the parts and additional fuel issupplied to the nozzles, assuming constant fuel pressure. The enlargedbore 93 acts as a well beneath the metering section in which, at alltimes, a reservoir of fuel is maintained. When the engine is operatingand the valve 7'5, '58 is partially open the well of fuel is underpressure. This arrangement insures a steady and uniform flow of fuelthroughout the annular space between the metering parts 84, H33.Moreover, since there is at all times a clearance at the meteringsection and fuel flows through this space under pressure, there islittle likelihood that the metering section will become clogged withdirt.

It will also be observed that a well of fuel exists below the fuelmetering valve. When the fuel metering valve is opened slowly thedisplacement of fuel in the well by the valve has almost no effectinsofar as increasing the fuel flow through the metering section of thevalve. However, if the engine is being accelerated rapidly, thedisplacement of the liquid in the well causes momentarily a somewhatincreased fuel flow through the metering section of the valve.

Of particular importance is the fact that the wall of the air fiowpassage (Fig. 1) from the point H6 which marks the closed position ofthe air metering disc, slopes outwardly and downwardly as shown at i H.The outward and downward sloping shape of the wall is accuratelydetermined so that for any part-open position of the air metering discand the fuel metering valve, the proper ratio of fuel to air will besupplied in accordance with the speed and load at which the engine isoperating. In general, the air flow passage is shaped so that the fuelto air ratio is decreased with increased air flow and heavier loadspreferably until approximately full throttle position is reached.

In Figs. 2, 3 and 4, I have shown a means for controlling the.temperature of air flowing to the carburetor: the air intake section I Sof the carburetor, I" have provided a. valve I'I oreferabl'y ofthebutterfly type The butterfly. valve is fixed toa shaft I-2I and theblades of the valve cn-oppositesides oftheshaf-t are of unequal wi'dfilrso that a flow' of airthrough the valve. tends tioswing the valve ina:counterclockwise direction, asviewedii'n Fig; 3', to move the valve an:openposition.

The tendency' of'the valve to: open is. resisted by a. thermostaticcoiled spring I22 one end of which; as shown at: I23 is attached tothevalve and the other end of which is wound about and attached to a.-

IZ I The spring I 22 is of the Iii-metallic type so that when. it issubjected tc heat it: expands: or: uncoils. The expansion permits thebutterfly valve to move toward anopen! position as dictated by: the. airflow: through the intake I 5.

biemetallic spring mounted in. a compertinent- IZ6 closed' bv a coverIZT, the-meeting surfaces of the margins of the opening and the cover I21 being sealed by a gasket- I ZU. A pipe I28 is connectedto thecarburetor, as shown at tit, and to an. air chamber [32 formed in theexhaust manifold N3, asshown at I 34. The hot gases discharged from theengine circulate throughpassageli36formed in the exhaust manifold andfresh. air is admittedto the air chamber I32 through openings" I31";

A second compartment: I138: is: formed in. the carburetor casting whichis also. closed by" the cover; I2I.. The compartment I38 is filled witha suitable material I39 which may be spun glass or noncorrosive metalwool, capable of removing dust and dirt which may" enter; the pipe I29.The walls ofthe compartment I38 are pro.- vided with suitableflowpassages IIIIi through which air" is supplied to the" compartmentI26. The function of the material" P39 is not only to filter" out dustand dirt particles but also to interpose, in the path of flow of airfrom adjacent the exhaust manifold, a resistance such that preferablywhen the butterfly valve is in a fully open position, no air will passthrough the pipe I29.

The purposeof the above arrangement is to enable a flow of warm air tothe carburetor when the engine is relatively cold and, at the same time,prevent a flow of warm air to the carburetor whenthe' engine is warm.Thus, when the thermost'atic spring I22 expands, due to the passage ofwarm air over it and the butterfly valve starts to open, the resistanceto flow of air fromthe exhaust manifold is such that the air supplied tothe carburetor through the pipe I29 is decreased. In the preferredarrangement, the flow of air to thecarburetor should cease whenthebutterfly valve is fully open.

One of the important features of the carburetor of my invention lies inthe fact that all the air passing to the carburetor is metered air sinceall the air passes through the opening controlled by the air meteringdisc I9. In the conventional arrangements with which I 'am familiar, thewarm air from adjacent the exhaust manifold is supplied to the intakemanifold at a point below the air metering device and usually below the.1,;throttle valve. This by-passed air is unmetered.

When the engine is initially started and is cold, "the air metering discI9 moves to a partially open position, as dictated by the differentialin pressure on opositesides. offthe disc. The air is drawn. fromadjacent the exhaust-manifold which heats up very rapidly, causing inaddition to an expansion. of? the thermostatic spring. I22; an.expansion of" the. thermostatic spring 92*. which. normally closes theports. 9|. through the: air metering disc. Assuming the engine ispermitted to warm. up at idling speed. the opening of the ports occurs:with the engine operating at the same. speed. Upon opening the ports 91:the. pressuresv differential on opposite sidesiof' the air meteringdiscis increased", thereby permitting the air metering: disc. tomove to.a more nearly-- closed position to thereby cutdown the flow of fuelthrough the fuel" metering valve without av corresponding decrease inthe flow'oi air; If the engine is operated at relatively high speed.when cold, the same effect. is. produced. the-.fuel-air ratio; beingdecreasedv as the engine warms up.v

It. is: contemplated, inv the preferred arrange.- ment',. that: no. airshall: be drawn from. the. exe haust: manifold when. the. engine up to.temperature and. the. butterflyvalve H9 is in its fnlly openposition;For thiE'DllI'POSB an adjustmg knob. M32 is provided. which enables. theadjustment. of? the tension at the thermostatic element. I Z2; Uporrrotating the. adjustment knob. WI in a clockwise direction, aided: byas. suitable. scale I435, the. tensionof the thermostatic spring.element: t2 2; maybe lessenedl so. that the butterfly valve reaches. aiullyopen'. position somewhat prior to. the engine. reaching its runningtemperature; V,

It? will be. appreciated; that if the: engine. is being" driverrin cold.weather, the. air under the hood; may be: relatively acid. This cold:air" will have an: efiect; on; the thermostatic: spring I22 contracting:it, closing: the. butterfly valve some.- what and: drawing some: warm.from. adjacent the exhanstzmanifold. If desired, the knob: M2 adjustedso-thatat allltinres some air: is drawn from. the. exhaust. manifold.or. theqlsnob may be adjusted for summer and winter driving.

' However, it will be apparent that I have provided a means forcontrolling the temperature of the air flowing to the carburetor.

When the engine is at its running temperature,

, assuming normal atmospheric temperature conbeneath the hood of the nowwarm engine. I

contemplate adjusting the theromstatic spring element so that when theengine is operated on warm days; the ports will be at least partiallyopen without the engine being warm, as when the atmospheric temperatureis high little or no additional fuel is required at starting. Onextremely cold days the ports may never fully open if the temperature ofthe air beneath the hood does not rise sufiiciently. It will beparticularly noted that all the air passing to the carburetor ismetered, the opening of the ports merely decreasing the fuel-air ratiofor any particular set of conditions.

pivoted to the end thereof, as shown at I 5| The link has a lost motionconnection I52 to a rocker arm I53 pivoted at I54.

The rocker arm I53 carries an adjustable screw I56 which is adapted toengage a cam l5! having a lobe I53. The cam is mounted on the projectingend of the butterfly valve shaft I2I (Fig. 3). The rocker arm I53 has atail piece I 59 which is adapted to engage a cooperating tail piece I6Iformed on the cam.

When the engine is cold the parts are in the approximate position shownin Fig. 5 with the cam lobe I58 limiting the closing of the throttlesince the arm EM moves in a clockwise position to close the throttle.Itwill be noted that the lost motion connection I52 is at the bottom ofthe slot and the engagement of the screw with the cam lobe limitsclockwise movement of the arm I44 and hence the closing of the throttle.

I As the engine warms up the cam moves clockwise, as viewed in Fig. l,in'accordance with the opening of the butterfly valve. This permits thethrottle to close more fully. When the engine is warmed up, the end ofthe screw I55 is out of engagement with the eam lobe and control of thethrottle, because of the lost motion connection,

when presumably the engine is at running temperature and the butterflyvalve should be open.

While I have shown the preferred form of the carburetor of my inventionit will be apparent that various changes and modifications may be madetherein, particularly in the form and relation of parts, withoutdeparting from the spirit of my invention as set forth in the appendedclaim.

Should the 2 I claim:

In a carburetor wherein an air passage is connected to a variable sourceof temperature of air supply and a throttle valve is located in said airpassage comprising, in combination, an air metering valve movable from aposition substantially to closing said passage to an open position inaccordance with the pressure conditions existent in said air passage,said passage having an opening to atmosphere and an opening connected tothe variable source of temperature of air supply, a valve normallyclosing the opening to atmosphere, a thermostatic spring elementconnected to said valve and to maintain said valve closed whereby theair supply for the carburetor is drawn from the variable source oftemperature of air supply, said passage and the opening thereto beingarranged so that the air from the variable source of temperature of airsupply passes over said thermostatic spring element and all of the airfrom both said openings passes through the air metering valve, said airmetering valve having a port, a thermostatic element normally closingsaid port, said thermostatic element moving toward an open position whenthe volume of air drawn from the variable source of temperature of airsupply is reduced due to the action of said thermostatic spring element.

FRANK B. SWEENEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,502,219 Wallace July 22, 19241,356,238 Bracke May 3, 1932 1,968,553 Heitger July 31, 1934 2,108,556Hardt Feb. 15, 1938 2,139,355 Coffey Dec. 6, 1938 2,325,372 Cofiey July2'7, 1943

